Global warming stopped in 1998 ? Re: [asa] Claude Allegre, one of France's leading socialists and among her most celebrated scientists, was among the first to sound the alarm about the dangers of global warming.

I will take a look at some of the other assertions in Inhofe's 'press
release' this time the statement that "Global Warming" Stopped in 1998

<quote>Paleoclimate scientist Bob Carter has noted that there is
indeed a problem with global warming â€“ it stopped in 1998. "According
to official temperature records of the Climate Research Unit at the
University of East Anglia in the UK, the global average temperature
did not increase between 1998-2005. "â€¦this eight-year period of
temperature stasis did coincide with society's continued power station
and SUV-inspired pumping of yet more carbon dioxide into the
atmosphere," noted paleoclimate researcher and geologist Bob Carter of
James Cook University in Australia in an April 2006 article titled
"There is a problem with global warming... it stopped in 1998." See:
http://www.telegraph.co.uk/opinion/main.jhtml?xml=/opinion/2006/04/09/do0907.xml&sSheet=/news/2006/04/09/ixworld.html
</quote>

This statement is misleading since the full data set since 1998 shows
quite the contrary.

<quote>
Consider the simple fact, drawn from the official temperature records
of the Climate Research Unit at the University of East Anglia, that
for the years 1998-2005 global average temperature did not increase
(there was actually a slight decrease, though not at a rate that
differs significantly from zero).
</quote>

Again the reality is simple and quite a different picture emerges (of
course now that it is 2007, we have even more evidence that Carter was
wrong)

<quote>
"Global Warming stopped 8 years ago because it was warmer in 1998 than
now." This argument is clearly lacking in substance. 1998 was a record
high year, and according to NASA GISS, it was elevated .2oC above the
existing trend line by the strongest El Nino of the century. Choosing
that year as a starting point is a classic cherry pick and
demonstrates why it is necessary to remove the very chaotic
inter-annual variability that exists in the annual mean. Looking at
the NASA graph above you can see the smoothed line in red, which
represents a 5 year mean (thus it stops in 2003 as we won't know the
mean for 2005 for two more years).

Interestingly, Bob Carter seems to know what he is doing and tries to
preempt objections by basically insinuating that any choice of
starting point, (such as 1978), will just be a cherry pick with the
opposite motive! But cherry picking is about choosing data for the
sole purpose of supporting a pre-conceived conclusion, it is not the
simple act of choosing at all, one must choose something. In the case
of the year 1978, this is often chosen simply because it is the first
year that satellite records of tropospheric temperatures were
available.

So what choices are there, what reasons for those choices and what are
the conclusions?

As mentioned above, one could chose to examine the last 30 years
because that is the period of time where both surface and tropospheric
readings were available. We have been experiencing warming of
approxiamately .2 oC/decade during this time.

You could choose 1970 in the NASA GISS analysis as this was the start
of the late 20th century warming. The surface record over this period
shows .6oC warming.

You could choose 1965 in the CRU analysis as this is when the recent
warming started in their record. This record shows around .5 oC
warming of the smoothed trend line.

You could choose 1880 or 1855 in the NASA or CRU records above as that
is when they started. This shows .7 and .8oC warming respectively.

You could choose to look at the last 500 years in the bore hole record
analysis because that is its entire length. This puts us about 1 oC
above the temperatures in the first 3 centuries of that record.

You could choose to look at the last one thousand years, because that
is as far back as the dendrochronology studies go. Then the conclusion
is:

Although each of the temperature reconstructions are different
(due to differing calibration methods and data used), they all show
some similar patterns of temperature change over the last several
centuries. Most striking is the fact that each record reveals that the
20th century is the warmest of the entire record, and that warming was
most dramatic after 1920.

You could choose to look at the entire period of time since the end of
the last ice age, around 10kyrs ago. Then the conclusion is that GHG
warming has reversed a very long and stable period with a very slight
downward trend and we are now at a global temperature not experienced
in human civilisation, or the entire Holocene.

I think that about covers any periods of time relevant to today's
society. Clearly, "it is not warming" is only shallowly suported by a
single choice of a specific year. That is a classic cherry pick.
</quote>